zafira 1.8(02/52) misfire?

. car is also duel fuel sadly no longer conected.while checking under bonnet noticed (since accident repair) air intake to air filter not fitted properly, also no filter(firm responsible no longer in exsistance) so refitted pipe cleaned leaves out and have just bought new air filter which way up does it go.. big fins up or down but engine management lite on now and runs rough..l